On Sun, Aug 04, 2024 at 09:30:16PM -0400, Waiman Long wrote:
Commit e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2") adds a user writable cpuset.cpus.exclusive file for setting exclusive CPUs to be used for the creation of partitions. Since then effective_xcpus depends on both the cpuset.cpus and cpuset.cpus.exclusive setting. If cpuset.cpus.exclusive is set, effective_xcpus will depend only on cpuset.cpus.exclusive. When it is not set, effective_xcpus will be set according to the cpuset.cpus value when the cpuset becomes a valid partition root.
When cpuset.cpus is being cleared by the user, effective_xcpus should only be cleared when cpuset.cpus.exclusive is not set. However, that is not currently the case.
# cd /sys/fs/cgroup/ # mkdir test # echo +cpuset > cgroup.subtree_control # cd test # echo 3 > cpuset.cpus.exclusive # cat cpuset.cpus.exclusive.effective 3 # echo > cpuset.cpus # cat cpuset.cpus.exclusive.effective // was cleared
Fix it by clearing effective_xcpus only if cpuset.cpus.exclusive is not set.
Fixes: e2ffe502ba45 ("cgroup/cpuset: Add cpuset.cpus.exclusive for v2") Reported-by: Chen Ridong chenridong@huawei.com Signed-off-by: Waiman Long longman@redhat.com
Applied 1-2 to cgroup/for-6.11-fixes w/ stable cc'd.
Thanks.